I found this pretty burgundy dress at the local thrift store for only $8. It was fully-lined and had a fun fishtail detail at the back. It had a high neck and sleeves. Unfortunately, however, the V-shaped back was open almost to the waist. But because the dress had a cowl overdrape in the back, it was possible to create a fill-in for the low back. The fun thing about the finished fix is that it echoes the fishtail at the bottom of the dress.

Front	Back Before (cowl is at front)	Back After	Before and after, closeup

Instructions

1. Carefully clip the shoulder seam stitching at one shoulder, where the cowl is attached. Pull the cowl away from the shoulder seam completely. Drape to see how high up it needs to come in order to provide the necessary coverage.
      

2. Note how the cowl was pleated, because you will need to later re-pleat the shortened cowl the same way the original was pleated. Gather up the excess and cut (save the excess for use later). Re-pleat the shortened end.
      

3. Insert the shortened cowl back into the open shoulder seam and pin in place. Stitch cowl to shoulder, being careful to sew through all layers of the pleats. Then carefully whip-stitch the shoulder seam back closed, taking tiny stitches. When this is done, you will note that there is still a triangle of bare skin above the zipper.
    

4. Using the excess that was cut off the cowl, pleat it into a fan shape. Arrange it so that it covers the bare triangle, and hold in place against the shortened cowl. Carefully blind-stitch it in place. For further coverage, pinch the cowl together in a deep fold, then tack the sides together as shown.